The present invention relates generally to the field of electro-optics, and more particularly to an organic electro-optic device and method for making the same.
Organic electro-optic devices include organic light emitting devices (OLEDs) and organic photovoltaic devices, for example. An OLED typically comprises one or more semi-conducting organic thin films sandwiched between two electrodes, one of which is usually transparent. When a forward bias is applied, injected electrons and holes recombine in the organic layers to generate light. Organic light emitting devices have great potential in the display and lighting industry. Due to their increased brightness, faster response time, lighter weight and lower power consumption, OLED displays are expected to replace liquid crystal display (LCD) applications in the near future.
Another type of organic electro-optic device is a photovoltaic device. A photovoltaic cell typically comprises a pair of electrodes and a light-absorbing photovoltaic material disposed therebetween. When the photovoltaic material is irradiated with light, electrons that have been confined to an atom in the photovoltaic material are released by light energy to move freely. Thus, free electrons and holes are generated. The free electrons and holes are efficiently separated so that electric energy is continuously extracted. An organic photovoltaic device typically has a similar material composition and/or structure as an OLED yet performs an opposite energy conversion process.
Organic light emitting devices are traditionally fabricated in a batch process by sequentially depositing the organic thin films followed by a thin metal cathode onto a transparent, anode-bearing substrate such as glass or a flexible plastic. A number of disadvantages exist with this manufacturing approach, however. For example, one or more vacuum processes are typically necessary to facilitate deposition of the organic materials and/or the metal electrode(s). The presence of vacuum processes greatly increases the cost of the much desired roll-to-roll (R2R) process where a roll of substrate can be continuously converted into a roll of product. In addition, since the cathode metal and active materials in an OLED are sensitive to air and water vapor and degrade rapidly if left unpackaged, it is often necessary to encapsulate traditionally fabricated devices in an inert gas ambient. These extra packaging process steps are typically lengthy and costly. With the traditional deposition processes, it can also be difficult to produce reliable OLED products with large area. Due to the vacuum process, the size of an OLED product manufactured with traditional methods is usually limited by the size of the high-vacuum equipment.
These and other drawbacks exist in known systems and techniques.